Apparatus for magnetic separation of materials



July 14, 1953 R c, HQFF 2,645,348

APPARATUS FOR MAGNETIC SEPARATION OF MATERIALS Filed June 25, 1949INVENTOR RON/ 1.0 C.HOFF

ATTORNEY Patented July 14, 1953 APPARATUS FOltMAGNETIC SEPARATION OFMATERIALS l Renal d0. Hoff, Erie, Pa., assignor to Eriez ManufacturingCompany, Erie, Pa., a corporation of Pennsylvania Application June 25,1949, Serial No. 101,432

14 Claims. 209-218) This invention relates generally to apparatus forthe magnetic separation of materials and more particularly to theseparation of non-magnetic materials from magnetic materials.

When the mixed materials to be separated contain a relatively highpercentage of magnetizable material, for example, from five to ten ormore per cent as compared to ordinary separation where the magnetizableparticles are usually measured in parts per 1000, the magnetizableparticles tend to be attracted to each other as well as toward and tothe magnet. In the past, it has been the practice to pass such mixedmaterials over a drum type separator of the agitator type. In this drumtype separator, a cylindrical shell is rotated around fixed magnetshaving alternating north and south poles around a portion of thecircumference. The magnetic material being carried around the drum iscaused to change polarity and a tumbling action results. This methoddepends upon the non-magnetic material falling away from the face of thedrum by gravity and in wet separation processes, with the aid of astreamof water washing the surface of the drum in a direction opposed toits rotation.

This method has never been too successful particularly with materials inthe dry state and with the finer non-magnetic materials since. 1

l. The finer non-magnetic particles tend to stick to the magneticparticles and to the surface of the drum and they become entrapped inthe bunched strings of magnetic .particles which have been attracted toeach other;

2. The mixed dry materials are usually introduced to the drum at thebeginning of a top quadrant thereof and gravity tends to remix thenonmagnetic and magnetic materials until the horizontal center line ofthe drum is approached allowing only the lower quadrant of the drum forthe non-magnetic material to fall free; and

3. It has never been possible to increase the separating efliciency ofan agitator. drum to any degree by the use of centrifugal force actingupon the non-magnetic materials since a. Impingement of the materialmixture on a rapidly revolving drum tends to throw the mixture away fromthe drum before it can become b.-Passing the magnetizable materialsthroug alternate poles of a magnet cause particles thereof to turn endover end and when the particles are standing on end, their attraction tothe magnet is greatly decreased whereby centrifugal force at this timecan readily throw it off. On wet separation, a considerable volume ofwater is required. p

It is, accordingly, an object of my invention to overcome the above andother defects in mag-.

netic separation devices of the drum type and it is more particularly anobject of my invention to provide apparatus for magnetic separation ofmaterials which is simple in construction, economical in cost,economical in manufacture, and efficient in operation.

Another object of my invention is to provide apparatus for magneticallyseparating finely divided materials utilizing a rotating magnetic memberwith successive stages of magnetic pole pieces of opposite polarityaround the periphery thereof.

Another object of my invention isto provide an inclined bafiie between amaterial delivering device and a magnetic drum with a rotating field. 1Another object of my invention is to, provide apparatus for separatingmaterials magnetically before reaching the face of a magnetized pulleycomprising a series of inclined baffles, thelbafiies being inclined atdifferent vertical angles from a horizontal plane passing through theaxis of the magnetic drum.

Another object of my invention is to provide a series of inclinedbafiles in the path of materials to be separated and in magnetic fieldsof opposite polarity of a magnetic drum, in association with conveyingbafiles or aprons for conveying the nonmagnetic material separated onthe baiiles from the magnetic material to a point adjacent the pulleyfor further separation. 7 Another object of my invention is to provide aseries of bafiles in a magnetic separating device between the deliverypoint of the material to be separated and a magnetic drum, the height ofthe baffles adjacent the drum being greater than those adjacent thedelivery point.

Another object of my invention is to provide a series of inclinedbattles between a delivery point of material to be separatedand amagnetic drum and means for pulsating or vibrating the bafiles upon therotation of the magnetic drum.

Other objects of my invention will become evident from the followingdetailed description, taken in conjunction with the accompanyingdrawing, in which The figure of the drawing shows a more or lessdiagrammatic side elevational view of my novel apparatus formagnetically separating material with the magnetic drum shown in crosssection.

Referring now to the drawing, I show in the figure of the drawing amagnetic drum I having circumferentially spaced, U-shaped magnets 2. Thepole faces of the magnets 2 are engaged with pole pieces or shoes 3disposed in spaced relation around the periphery of the drum I. Themagnets 2 are attached to the drum I by bolt and nut assemblies 6. Itwill be noted that by the use of three magnets symmetrically placedaround the inner periphery of the drum. I, six, equally spaced magneticpoles 9 of alternate polarity are provided around the periphery thereof.The magnetic fields I produced by the poles 9 are weakest adjacent thepoints of juncture 8 and strongest toward the central portion thereof asis well known in practice. The drum I has a non-mag neticbelt Illengageable therewith the belt I!) engaging any suitable power pulley forrotating the drum I:, preferably in a counterclockwise direction.

Associated with the drum I are a series? of baf to be separated to thecentral portion of the first bafile I2. I preferably utilize aconventional vibrating conveying trough in order to evenly distributethe material to be separated movable therein. The angle of inclinationof the bafiles I3, and I4 increases successively from the deliverytrough IE to the drum I as shown in the drawing, The balile I2 has theleast, angle of inclination and it has depending flanges I9. The

magnetizable material is drawn over the top side of thebafile. I2with'the. use of a comparatively small magnetic force provided by themagnets 2 in the drum, I. The non-magnetic material flows downwardly bygravity on the baffle I2 opposite to the direction. of movement of themagnetic material. onto a conveyingapron H which is attac-hed to thesupport plate I5 by means of brackets 22 and screw bolts23. The ends Zldof the.

apron 2| are flanged downwardly. The apron 2| is inclined in a directionopposite to the inclinae tion of the baffles I2, I3, and I4 so that thematerial flows. bygravity downwardly thereon in the general direction ofthe drum. I The battle.

I3 receives the material that moves. over the top of the baffle I2 andit hasv the upper end I3a thereof bent toa vertical position. Afterseparation on balile I3, the material that passes over the top thereofengages the midpoint of baffle lei where i more direct impingement onthe succeeding baffles. The upper ends I3c and Ma of the baflies l3 andI4 are bent to more thoroughly agitate the material passing thereoverwhereby the nonmagnetic material will be shaken loose from any bunchedmagnetizable particles. The baiile I4 has a right angled dependingbafile portion 24.

. the. drum I. The apron 25 is secured tothe plate I5 by means ofbrackets 25 and'screw bolts 21. The end 28 of the apron 25 is bentupwardly at right angles to prevent non-magnetizable material fromflowing toward the face of the belt I0 on the drum I and to thoroughlyagitate any remaining magnetizable particles impinging thereon due tothe strong attraction of the magnets 2 in the drum I. The lower end 29of the apron 25 is flanged. downwardly at right angles to permit thefree flow of non-magnetizable material therefrom. r 1

The support plate I5 has an aperture 3 I through which extends a supportshaft 32; the diameter of the aperture being greater than the shaft 32tov permit pulsating or vibratory movement of the support plate I5. An:armature 33 is supported on an arm 34 which extends angularly upwardlyfrom the upper end of the plate I5 and is secured theretoby welding orany other suitable means. The armature, 3.3- is made of: magnetizablematerial so that as it tends to close. the magnetic circuit between thenorth and south poles 9: of the magnets 2, it is moved inwardly. Uponcontinued rotation of the drum I, the armature 33 moves to a weak fieldand the. spring 35 urges it further separation takes place. The upperend Me of the baflle I4 isbent to an inclined position away' from thedrum I to minimize the amount of non-magnetic material carried thereoverto the belt I0. surrounding the drum I. The bafiles I2, 13, and 14 are.preferably arranged so. that the material flowing thereon strikesapproximately the midpoint thereof. The baffles. I2, I3, and [4preferably have successively greater angles of inclination in order thatthe finer nonmagnetizable materials carried with the magnetizablematerials over the bafIles I2 and I3 will be shaken from the.magnetizable material due to the outwardly. The armature 33:. is thusmovedinwardly and outwardly upon pass-age. of each pair of poles 9 ofthe magnets 2; thereby causing pulsating movement of the support I5. Thecom- 'pression spring 35 is supported by a bracket 36 and it engages thelower side of the support plate I5 remote from the drum I to urge thearmature 33 away from the drum I. The vibrating or pulsating movement ofthe baffles I2, I3, and I l permit the use of baffles with lessinclination thereby providing better separation The vibrations of thebaliles i2, I3, and I4 permit the use permitting the, magnetizableparticles to be walked up-over the baiiles end. over end more easily,particularly on the more. remote bafile I2 when the field is not asstrong.

In operation, the drum I is rotated by the belt Ill and material to be.separated is delivered to the first inclined baffle I2 at approximatelythe midpoint thereof by a conventional vibrating trough I6. Thevibrating trough I5 agitates the material to be separated sov that it isevenly distributed therein. The magnetic fields I of the magnets 2v ofthe drum I act upon the magnetiza ble particles in the materials to beseparated. when they reach a point near the end of the trough It in thepreferable form of my magnetic separating device. The magnetizableparticles tend to string or bunch together when they enter the. magneticfields of opposite polarity produced by succeeding poles 9 of themagnets 2.. The magnetic fields of opposite polarity cause the magendover end inasmuch as the field of one polarity magnetically induces thestring of magnetizable material causing the more distant end of thestring tobe'attracted by the approaching pole of opposite polarity. Thisaction repeats as the drum revolves causing the particles to walk endover end into the face of the drum. Bystringing together themagnetizable particles, the par ticles on the ends thereof have agreater amount of induced magnetism. When the material to be separatedreachesthe midpoint of the pulsating inclined bafile I2, thenon-magnetizable material gravitates downwardly on the baflle I2 to theinclined apron 2| whence it passes to the apron 25 and to a suitablecontainer. The magnetizable material is drawn upwardly over the upperend of the bafiie I2, end over end, impinges on the second baiile I3whereupon the magnetizable material moves upwardly thereon end over endand the non-magnetizable material carried with the magnetizable materialis shaken loose by the impingement and agitation of the magnetizableparticles drawn over the upper end Isa of the baffle I3 and gravitatesdownwardly on the baffle I3. Inasmuch as the baiiie I3 is in a strongermagnetic field than bafile I2 because it is closer to the drum I, theupper end I 341 of the baffle 13 is bentup- .wardly to a verticalposition to increase the agitation of the magnetizable particles toshake loose the non-magnetizable particles therefrom. When the remainingmaterial leaves the upper end I3a "of the baffle I3 and is drawn withincreased force into the baffle I4, it is violently agitated by theimpingement and non-magnetizable particles clinging to or held bymagnetizable particles are i shaken loose and they gravitate downwardlyon the baifie It! to the apron 24, the magnetizable imaterial moving endover end upwardly thereon clinging to or held thereby. The angle ofinclination of the baffles I2, I3, and [4 increases progressively fromthe delivery chute It to the drum I to progressively decrease the angleof impingement and increase the agitation of the magnetizable particlesto assure complete separation.

All of the separated non-magnetizable material gravitating from thebaflies l2, I3, and I4 pass to the apron 2! whereby they are directed toa. point adjacent the drum I.

As it passes from the lower end of the apron M to the upper end of theapron 25 adjacent the drum l, the material is again subjected to thestrong magnetic forces of the magnets 2 of the drum and any remainingmagnetizable material is drawn upwardly, end over end, over the bentupper end 28 of the apron 25 and it is gathered on the belt Isurrounding the drum I. The magnetic fields of opposite polarityproduced by the opposite poles 9 of the magnets 2 passing the armature33 causeit and connected plate I carrying baffles I2, I3, and I 4 topulsate thereby causing the material to be agitated at all times so thatit gravitates down the inclined bafiies I2, I3, and I4 and aprons 2| andcontinuously and the magnetizable par- 'ticles are agitated so that thebaffles I2, I3, and I4 may have a lesser inclination thereby minimizingi 6 the amount of magnetizable material gravitating with thenon-magnetizable material to the apron 2 I, The non-magnetizablematerial gravitates from the apron 2| to the apron 25 which passes thenon-magnetizable material to a point remote from the drum I. Themagnetizable material is gathered on the belt I0 surrounding the drum Iand any remaining non-magnetizable material is thrown off therefrom bycentrifugal force. The magnetizable material drops from the belt IIIwhen it reaches a point outside of the magnetic fields I of the magnets2. 7

Any type of delivery trough may be used but I prefer to use avibratorytype because it provides an even uniform flow which gives uniformresults. Although I show the baiiies I2, I3, and I4 attached to one sideof a plate [5, I show this for illustration only inasmuch as the hafilesmay be supported by plates on both sides thereof or by any othersuitable supporting means. My magnetic separating device will operatewithout the pulsation of the'support plate I5 althoughI prefer topulsate the support plate and the bafiles I2, l3, and [4 to assure theeflicient flow of the materials with bafiies having a minimuminclination. The armature 33' may be utilized for pulsating anyaccessory equipment in conjunction with the magnetic drum I. i

I prefer to use more thanone inclined baffle although it will be evidentthat my device will operate with only one inclined battle. I also preferto increase the inclination of the baffies as they become more distantfrom the delivery trough and as they move into the strongest field ofmagnetization of the drum I because only the more finely grainednon-magnetic material usually reaches the second and third baflles andincreased obstacles causing greater impingement frees a maximum amountof non-magnetizable material.

It will further be observed that the upper ends of each succeedingbaflle from the delivery trough to thedrum is spaced upwardly from thepreceding bafile and the upper end of the baffles nearest to the pulleyare inclined vertically or away from increasing the agitation and theconsequent throwing off of the non-magnetic materials.

The drum I has the magnetic pole pieces and air gap-running parallel tothe shaft supporting it so that when the drum revolves in front of thematerial to be separated or adjacent thereto, it causes the magneticparticles to tumble end over end in a pulsating action as the north andsouth magnetic fields intermittently magnetize the magnetic material asthe drum I rotates.

Itwill be evident from the foregoing description that I have provided amagnetic separating device for separating magnetizable materials andespecially materials containing an appreciable amount of magnetizablematerial wherein the material is run from a vibrating trough over one ormore inclined separating baffles interposed between the delivery chuteand the face of a belt on a magnetic pulley or drum, the magnetic drummaterial which gravitates with the non-magnetizable material from theinclined battles between the delivery chute and the pulley, which alsoseparates non-magnetizable material from the magnetizable material bycentrifugal forceafter it "rotating member having magnets spaced aroundthe inner periphery thereof and rotating therewith, said magnets havingalternately progressive magnetic poles of opposite polarity around theouter periphery thereof, an inclined bafiie spaced laterally from saidrotating member within the magnetic fields of said magnets therein,

and means for feeding the material to be separated onto the side of saidinclined baiile in a direction towards th magnets of said rotatingmember, said baffle being inclined away and downwardly from said memberwhereby non-magnetic material is directed therefrom by gravitation andmagnetic material is drawn over the top of said inclined balile towardsthe outer surface of said rotating member.

2. A magnetic separating device as set forth in claim 1 wherein aplurality of successively spaced inclined bailies are spaced laterallyfrom said rotating member, the angle of inclination of each successivebaffle beinggreater than the angle of inclination of the precedingbafiie in the direction of said rotating member.

3. In combination with a rotating member having magnets disposed aroundtheperiphery thereof providing magnetic poles of opposite polarityalternately and progressively around the periphery thereof, a pluralityof spaced inclined baiiles spaced laterally from said rotating memberwithin the magnetic fields of said magnets, the angle of inclination ofsaid bafiies being away from said rotating member, and means fordirecting material to be separated into said inclined bailles towardsaid rotating member whereby magnetizablematerial is attracted by themagnets in said rotating member over the top of said bafiies andnon-magnetizable material gravitates downwardly on said inclined bafiiesaway from said rotating member. 7

4. In combination with a rotating member" as .set forth in claim 3wherein the upperends of said bafiles adjacent said rotating member areinclined away from said rotating member.

5. In combination with a rotating member as set forth in claim 3 whereinsupport means are provided for said bafiies and an armature is mountedon said support means adjacent said rotating member for pulsating saidbaffles and baille support means.

6. In combination with a rotating member as set forth in claim 3 whereinan inclined apron is disposed below said baffles inclined toward saidrotating member to convey material gravitating from said baiil-es to apoint adjacent said magnetic rotating member whereby further separationof said material takes place.

7. In combination with a rotating member as set-forth in claim 6 whereina second apron is spaced from the end of said first apron and inclinedat an angle opposite thereto to direct non-magnetic material away fromsaid rotating member.

alternate north and south magnetic poles, a plu- .rality ofinclinedbaflles spaced laterally outwardly from said magnetic drum, saidbafiles be- .ing inclined away from said drum, means for deliveringmaterial to be separated into the bafiie furtherest from said magneticdrum toward said rotating member, an apron disposed below said bafflesinclined toward said rotating drum for directing the materialgravitating therefrom towards said magnetic drum, and a second apron 1spaced from end of said first mentioned apron to direct said materialflowing from said first mentioned apron away from said magnetic drum.

9. In a magnetic separating device as set forth in claim 8 wherein theangle of inclination of each of said successive inclined bafiies isinclined at a greater angle than thepreceding successive baflle fromsaid material delivery means to said magnetic drum.

10. In a magnetic separating device as set forth in claim 9 wherein saidbaflles are-disposed on a support member, and means are provided forvibrating said support member and baflies thereon.

11. In a magnetic separating device as set forth in claim 10 wherein themeans for pulsating said support member and baffles comprises an armsecured to-said support member having an armature adjacent said magneticdrum and in the rotating magnetic fields thereof.

12. In a magnetic-separating device, incom bination, a rotating memberhaving magnets disposed around the periphery thereof within saidrotating member defining alternate magnetic poles of opposite polarity,a deflecting member in the magnetic fields of said magnets spaced apredetermined distance laterally outwardly from the outer surface ofsaid rotating member for deflecting the flow of material attracted tosaid rotating member, and an armature connected to said deflectingmember disposed adjacent said rotating member in the magnetic fields ofsaid magnets for pulsating said deflecting member upon rotation of saidrotating member. V

13. In a magnetic separating device, in combination, a pulleyhavingmagnets of generally U-shape disposed around the inner periphery thereofwith the legs thereof transversely aligned around the periphery of saidpulley defining progressive magnetic fields of alternate polarity aroundtheouterperiphery of said pulley; a nona magnetic belt trained on saidpulley, a delivery chute for material to be separated having thedelivery end thereof in said magnetic fields, an V V inclined bafliedisposed between said chute and said pulley, said bafiie being inclinedaway from said pulley, and a second baffle inclined oppositely to thedirection of said first bafile to direct material gravitating therefromtowards and adjacent to said belt on said pulley, said material beingfed by said delivery chute into said inclined baffle in a directionleading to said pulley.

14. In a magnetic separating device, in combination, a rotatable memberhaving magnets rated passing toward said rotatable member to Number Name7 Date deflect the path of same, mounted on said sup 463,305 HoffmanNov. 17, 1891 port member for said armature. 500,604 Payne Ju1y'4, 1893RONALD C. HOFF. 634,356 Kreuser Oct. 3, 1899 5 946,394 Ohm Jan. 11, 1910References Cited in the file of this patent 1 529 970 which Man 17' 1925UNITED STATES PATENTS 1,693,033 Hope NOV. 27, 1928 Number Name Date 2,17,637 Sutton Jan. 16, 1940 411,899 Mofi'att Oct. 1, 1889 FOREIGN EN443,044: Finney DEC. 16, 1890 Number Country D te 449,726 Ball 7, 1891103,310 Austria, May 10, 1926

